• It should be random: A random sample is one in which each item in the sample has an equal chance of being selected. Statistical inferences may not be valid unless the sample is random.

  • It should be representative: the sample should be representative of the differing items in the whole population. For example it should contain a similar proportion of high and low value items of the population.

  • Protective: Protective of the auditor. More intensive auditing should occur on high value items known to be high risk.

  • Unpredictable - client should not be able to know which items will be examined.